3 consecutive sync updates will result deletion

[darkdh]

Description

Steps to Reproduce

1. Go to chrome://flags/#brave-sync and enable brave-sync on device A and B
2. Sync device A and B
3. Create folder/url1 on device A
4. Rename folder/url 1 to 12 on device B
5. Rename folder/url 12 to 123 on device A
6. When device B get UPDATE record, the folder/url will be deleted

Actual result:

folder/url 123 is deleted

Expected result:

device B should see folder 123

Reproduces how often:

100%

Brave version (brave://version info)

Version/Channel Information:

Version 1.6.18 Chromium: 80.0.3987.87 (Developer Build) (64-bit)

• Can you reproduce this issue with the current release?
• Can you reproduce this issue with the beta channel?
• Can you reproduce this issue with the dev channel?
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

[darkdh]

it is removed by
https://chromium-review.googlesource.com/c/chromium/src/+/1871593

[btlechowski]

LGTM

Verification passed on

Brave	1.6.24 Chromium: 80.0.3987.100 (Official Build) nightly (64-bit)
Revision	3f00c26d457663a424865bbef1179f72eec1b9fe-refs/branch-heads/3987@{#864}
OS	Ubuntu 18.04 LTS

Folders:

URLs:

Experienced 2 issues while testing:

• recreating sync chain can sometimes result in an empty/broken sync chain.
• renaming the same item at the same time on different devices will discard one change.
  I will investigate if I can reproduce.
  edit: Talked to @darkdh . Those issues are unrelated to the PR at hand.

[GeetaSarvadnya]

Verification passed on

Brave	1.3.116 Chromium: 80.0.3987.106 (Official Build) (64-bit)
Revision	f68069574609230cf9b635cd784cfb1bf81bb53a-refs/branch-heads/3987@{#882}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified the STR from the description
  

---

Verification passed on

Brave	1.3.116 Chromium: 80.0.3987.106 (Official Build) (64-bit)
Revision	f68069574609230cf9b635cd784cfb1bf81bb53a-refs/branch-heads/3987@{#882}
OS	Linux

• Verified steps from issue descrition
  

---

Verified passed with

Brave	1.3.116 Chromium: 80.0.3987.106 (Official Build) (64-bit)
Revision	f68069574609230cf9b635cd784cfb1bf81bb53a-refs/branch-heads/3987@{#882}
OS	macOS Version 10.14.6 (Build 18G3020)

• Verified STR from the description for both Folder and URL

Folder:

URL: